[vtkusers] PointInPolygon works strange

[Marco Nawijn]

Dear Shinpei,

I have never used this class/method before, but can it be a matter of
definition? In my opinion you have the interior and the boundary defined by
the polygon. I can imagine that "PointInPolygon" checks if the point is in
the interior, so it excludes points on the boundary. Since your point is on
the boundary, it would then be outside of the polygon.

Kind regards,

Marco



On Wed, Jul 10, 2013 at 2:27 AM, shinpei <noro_shinpei at web.de> wrote:

> Hi,
>
> I tried the example  PointInPolygon
> <http://www.vtk.org/Wiki/VTK/Examples/Cxx/Utilities/PointInPolygon>   with
> the following code:
>
> int main()
> {
>     vtkNew(vtkPolygon, polygon);
>     polygon->GetPoints()->InsertNextPoint(0.0, 0.0, 0.0);
>     polygon->GetPoints()->InsertNextPoint(0.0, 10.0, 0.0);
>     polygon->GetPoints()->InsertNextPoint(10.0, 0.0, 0.0);
>
>     double testIn[3] = {5.0, 0.0, 0.0};
>
>     double n[3];
>     polygon->ComputeNormal(polygon->GetPoints()->GetNumberOfPoints(),
>
> static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),
> n);
>
>     double bounds[6];
>     polygon->GetPoints()->GetBounds(bounds);
>
>     std::cout << "testIn in polygon? " <<
>
> polygon->PointInPolygon(testIn,polygon->GetPoints()->GetNumberOfPoints(),
>
> static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)),
>                                          bounds, n) << std::endl;
>     return EXIT_SUCCESS;
> }
>
> But the result is: The Point (5 0 0) is not in the polygon. This could not
> be the right result. The point rests on the edge (0 0 0) - (10 0 0) of the
> triangle.
>
> What is wrong?
>
>
>
> --
> View this message in context:
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> Sent from the VTK - Users mailing list archive at Nabble.com.
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